[Mesa-dev] [PATCH] ac/radeonsi: fix CIK copy max size

[Christian König]

Am 29.08.2018 um 05:53 schrieb Dave Airlie:
> From: Dave Airlie <airlied at redhat.com>
>
> While adding transfer queues to radv, I started writing some tests,
> the first test I wrote fell over copying a buffer larger than this
> limit.
>
> Checked AMDVLK and found the correct limit.
>
> Cc: <mesa-stable at lists.freedesktop.org>
> ---
>   src/amd/common/sid.h | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/src/amd/common/sid.h b/src/amd/common/sid.h
> index 0671f7d3998..edb7d06afa6 100644
> --- a/src/amd/common/sid.h
> +++ b/src/amd/common/sid.h
> @@ -9139,7 +9139,9 @@
>   #define    CIK_SDMA_PACKET_SEMAPHORE               0x7
>   #define    CIK_SDMA_PACKET_CONSTANT_FILL           0xb
>   #define    CIK_SDMA_PACKET_SRBM_WRITE              0xe
> -#define    CIK_SDMA_COPY_MAX_SIZE                  0x3fffe0
> +/* There is apparently an undocumented HW "feature" that
> +   prevents the HW from copying past 256 bytes of (1 << 22) */
> +#define    CIK_SDMA_COPY_MAX_SIZE                  0x3fff00

Well that is interesting. IIRC, the hardware documentation explicitly 
states that 0x3fffe0 is the maximum size.

That would also explain a couple of problems we see with on CIK because 
the kernel doesn't get that right either.

Christian.

>   
>   enum amd_cmp_class_flags {
>   	S_NAN = 1 << 0,        // Signaling NaN